Pumping system for oil burners



Nov. 7, 1933 J. L. MUELLER PUMPING SYSTEM FOR OIL BURNERS Filed Jan. 9, 1930 2 Sheets-Sheet l gme'nto'a J1. M05115? Nov. 7, 1933- J. L. MUELLER 9 9 PUMPING SYSTEM FOR OIL BURNERS Filed Jan. 9, 1930 2 Sheets-Sheet 2 1L MUELL 5/ Patented ,Nov. 7, 1933 UNITED STATES PATENT OFFICE 9 Claims.

This invention relates to pumping systems for oil burners, and more particularly to a system for supplying oil and primary air under pressure to an oil burner or other liquid fuel consuming device.

In the provision of systems for supplying oil to burners, it is the common practice to supply primary air to the burner for the oil, and to provide a draft opening in the boiler through which secondary air for supporting combustion is supplied. Extreme difliculty has been experienced in providing a properly proportioned mixture of oil and primary air, and the disturbance of the proper adjustment of the proportions of oil and primary air greatly affects the efficiency of combustion.

In the usual oil burner systems, float controlled means usually is employed for controlling the rate of flow of oil to the burner in accordance with the 20 demands of the latter, and it has been found that with the use of lower grades of oil, the float and the movable parts associated therewith are rendered inefficient in operation by the collection thereon of the relatively heavy constituents of the oil. Accordingly it frequently happens that a float will fail to work after being in operation for a considerable length of time, and accordingly the burner, and sometimes even the flller surrounding the boiler, will become flooded with oil.

It is the usual practice to provide compressor means for pumping oil and primary air whereby they may be supplied to the burner under the desired pressure. The flow of the oil is relatively slow, and it has been found that the pressure and friction present in the compressors generate a considerable amount of heat, and accordingly the compressors frequently operate under excessive temperatures.

As is well known, the usual types of domestic and industrial oil burners operate with considerable noise, and such operation is particularly objectionable in connection with domestic burner systems. The roaring sounds commonly present with burners of this character have been found to be largely due to the rapid rate of flow of secondary air into the combustion chamber, and it has been found that this is objectionable not only from the standpoint that it results in noisy operation, but it also tends to retard combustionthrough too rapid a flow of cold air into contact, with the flame, and it creates too great a stack effect tending to carry the products of combustion too rapidly through the furnace.

An object of this invention is to provide a novel compressor for supplying oil and primary air to the burner, wherein the fuel oil is utilized for cooling the compressor to prevent the letter from operating under excessive temperature conditions.

A further object is to provide novel means for controlling the flow of fuel wherein relatively heavy fuels may be employed without interference with the control mechanism whereby the latter is adapted to function properly under all conditions and after long periods of use.

A further object is to provide novel fuel supply control means which is operable by the weight of the fuel, and to provide novel means for adjusting the fuel supply control means.

A further object is to provide novel means for mixing the proper proportion of oil and primary air to be supplied to the burner, wherein the oil and air governing means may be initially set to govern the proportion of air and oil whereby the device subsequently may be manually adjusted as to the quantity of air and oil supplied to the burner without disturbing the proportions between the oil and air.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the drawings I have shown one embodiment of the invention. In this showing,

Figure l is a central vertical sectional view through the fuel supply and control apparatus, parts being shown in elevation,

Figure 2 is a plan view of the same, parts being broken away,

Figure 3 is a section on line 3-3 of Figure 2, parts being broken away,

Figure 4 is a section taken substantially on line 4-4 of Figure 3,

Figure 5 is a section taken substantially on line 5-5 of Figure 1, parts being broken away,

Figure 6 is a detail section on line 6-6 of Figure 5, v

Figure '7 is a similar view on line '7-7 of Figure 5, and,

Figure 8 is a detail perspective of parts of the oil and air proportioning device.

As previously stated, the present invention relates particularly to a system for supplying oil and air under pressure to an oil burner. As will become apparent, the system is not in any sense limited to use with a particular type of burner, but may be used with any type which may be suitable, and it also will be apparent that the system is applicable for use in supplying any liquid fuel and primary'air to a liquid fuel consuming device other than an oil burner. The apparatus however, is particularly intended for use with oil burners wherein oil and primary air are supplied thereto under pressure.

The oil and primary air supplying and controlling apparatus is illustrated in Figures 1 to 8 inclusive. Referring to Figures 1 and 2, the numeral designates a suitable base or support as a whole, the central portion of which is preferably somewhat elevated as at 96. One end of the base 95 is supported upon feet 97, and the corresponding end of the base forms a motor supporting platform 98.

A base plate 99 is mounted over the platform 98 and is spaced therefrom by suitable shims 100 preferably formed of live deformable rubber. Screws or similar fastening elements 101 are adapted to connect the plate 99 to the platform 98, and a motor 102 is mounted upon the plate 99. 1 The motor is provided with a drive shaft 103, and it will be apparent that the height of the axis of this shaft may be varied within reasonable limits by compressing the shims 100 to permit these elements to expand somewhat by proper manipulation of the screws 101. In connection with the latter mounting, attention is invited to the fact that the present apparatus is particularly intended for use in connection with standard commercial motors of suitable fractional horsepower. Various makes of such motors are substantially the same in size, but they vary slightly in the distances from the lower extremities of the motors to the axes of the motor shafts. The motor mounting described permits the use of different makes of motors which vary slightly in the respect referred to whereby the shaft 103 may be properly alined with respect to the elements adapted to be driven thereby.

A compressor indicated as a whole by the numeral 104 is adapted to be driven by the motor 102. This compressor includes amain substantially circular body 105 and a head 106. The body 105 is not connected to the base 95, and this construction is provided in order that the apparatus as shown may be adapted for use in connection with compressor bodies of varying axial lengths according to the quantities of the oil to be pumped. The head 106 is provided with an axially extending boss 107, and beneath this boss, the head is provided with a preferably integral base portion 108, connected to the boss 107 by a web 109, and the base 108 is adapted to be connected to the support 95 by suitable screws or bolts 110.

Referring to Figures 1 to 4 inclusive, it will be noted that the body 105 is cored out circumferentially as at 111 to provide a cooling jacket through which the oil to be pumped initially passes to provide a cooling medium for the compressor. A supply pipe 112, connected to a suitable source of oil supply, extends beneath the raised portion 96 of the support 95, and has its end turned upwardly as at 113 for connection with an intake port 114 communicating with the passage 111. The upper end of this passage is provided with an outlet port 115 communicating with a pipe 116 which conducts the oil to a flow control mechanism to be referred to later.

The compressor head 106 is provided with inlet and outlet ports 117 and 118 respectively, the latter of which is connected to the pipe 13 to supply oil to the burner. The inner ends of the passages 11'? and 118 communicate respectively with ports 119 and 120. The ports 119 and 120 communicate with a substantially cylindrical pumping chamber 121 formed in the body 105.

A rotor indicated as a whole by the numeral 122 is rotatable eccentrically within the pumping chamber 121 and includes a pair of separable parts 123 and 124,.the former of which is provided with an axial cylindrical extension 125 fitting within the part 124. The two parts of the rotor are secured to a drive shaft 126 to be rotated thereby. The rotor is provided with slots 127, arranged radially with respect to the rotor, and sliding vanes 128 are' arranged in the slots 127. The space provided between the rotor parts 123 and 124 receives a spring 129, preferably formed of wire, and having its ends tapered and overlapping to permit circumferential expansion. The spring contacts with the inner edge of each of the vanes 128 and exerts an outward pressure thereaga'inst whereby the outer ends of the vanes are caused-to be snugly seated against the cylindrical surface of the pumping chamber 121.

It has been found that the use of separate springs for urging the vanes of the compressor outwardly possesses a serious disadvantage in that each spring is subjected to considerable variation in length during the operation of the compressor whereby crystallization of the springs soon results in the breakage thereof. The use of the wire spring described is advantageous not only from the standpoint of economy but also from the standpoint of operation. For any given position of the rotor and the vanes 128, the spring 129 remains substantially circular, and since the spring alters its shape only to a slight extent, it is not subject to crystallization or breakage.

The body 105 of the compressor is provided with a boss carrying a bearing 131 arranged in axial alinement with a bearing 132 carried by the head 106. These bearings are arranged eccentrically with'respect to the pumping chamber 121 and they rotatably support the shaft 126 to which the rotor is secured. The boss 107 is provided with suitable packing 133 retained in position by a gland 134, and thus leakage of oil around the projecting portion of the shaft 126 will be prevented. As shown in Figure l, the shaft 126 is secured to the motor shaft 103 by a coupling 127'.

Referring to Figures 1 and 2, the numeral 128' designates a casing forming a measuring chamber in which the rate of flow of oil to the compressor is determined. It will be noted that the bottom of the casing 128 lies in the same horizontal plane as the bottom of the feet 97 of the support 95, and consequently the casing 128 acts as a support for the adjacent end of the apparatus. A protecting cover 129' is provided for the motor and compressor, and this cover extends downwardly as at 130 to form a partial cover for the receptacle 128. This cover is secured in position above the casing 128' by screws 131, and at its opposite end, it is secured to the base 95 by screws 132.

A cross member 133' is carried by the cover 129' and extends transversely across the casing 128' centrally thereof. The cross member is secured at its ends to the casing 128 by screws 131', as shown in Figure 2. The cross member 133 is provided centrally thereof with a raised I portion 135 the central portion of which is cylindrical as indicated at 136 to form an oil inlet chamber. cap 137 to which the oil pipe 116 is connected by a suitable union 138 as shown in Figure 1, and accordingly it will be apparent that oil passing from the cooling jacket 111 of the compressor will be supplied to the chamber 136.

This chamber is closed by a head or 1 The cross member 133' is provided with a yoke including depending arms 139 and a connecting cross member 140 arranged within the chamber 128'. A stem 141, arranged axially with respect to the chamber 128', is secured at its lower end to the cross member 140 by a set screw 142 and extends upwardly therefrom. This stem is threaded throughout the greater portion of its length as shown. A sleeve 143 is threaded on the stern 141 and is provided with an operating handle 144 extending radially from the sleeve 143 and thence upwardly as at 145 adjacent the side wall of the casing 128'.

A receptacle 146 is arranged within the casing 128' and is preferably provided with an open top as shown in Figure 1. This receptacle is provided with a central hollow boss or sleeve 147 which slidably receives the upper end of the sleeve 143 and extends upwardly therebeyond a substantial distance. A coil spring 148 is arranged between the upper end of the sleeve 143 and the upper extremity of the bore of the sleeve 147. Oil is supplied to the receptacle 146 in a manner to be described, and it will be obvious that the receptacle will move downwardly as the quantity of oil therein increases, against the tension of the spring 148.

The cylindrical chamber 136 is provided in its lower end with a plug 149 having a pair of valve seats 150 and 151 formed therein, the former affording communication between the chamber 136 and the interior of the chamber 128' through a passage 152. The sleeve 147 carries an upwardly extending valve stem 153 upon the upper end of which is arranged a valve 154 adapted to engage the seat 150. A ball valve 155 is arranged above the valve 154 to be engaged thereby, and is adapted to engage the seat 151.

As previously stated, a portion of the cover 129' extends over the chamber 128-, and the outer side of this chamber is preferably closed by a removable cover plate 156 secured in position by a screw 157. The plate 156 may be provided with one or more lips 158 adapted to engage beneath the cross member 133'. The cover plate 156 may be removed to provide access to the handle 145, and the chamber 128 may be detached from the support 95 by removal of suitable securing bolts 159.

A pipe 160 extends through a suitable opening in the inner wall of the chamber 128 and has its end turned downwardly as at 161 within the receptacle 146 and extending to a point near the bottom thereof. The other end of the pipe 161 is connected by a suitable union 162 to an oil and primary air proportioning device indicated as a whole by the numeral 163. The desired level of the oil within the receptacle is indicated by the dotted line 164, and it will be apparent that this line is arranged slightly below the center of the proportioning device 163, to prevent any oil from syphoning into the latter when the compressor is not in operation, as will become apparent.

The oil and air proportioning device is shown in detail in Figures 5 to 8 inclusive. Referring to Figure 5, the numeral 164 designates the body of the device which is substantially cylindrical, and the inner end of the body is connected to a threaded nipple 165. Inwardly of the nipple 165, the body 164 is provided with a bore 166 in which is arranged a plug 167 (see Figures 6 and 8). The plug 167 is provided with a plurality of longitudinal slots 168 out into the outer surface thereof to afiord communication between the nipple and an enlarged bore 169 formed in the outer en of the body 164.

Intermediate its length, the plug 167 is provided with a small axial passage 170 communicating with a radial passage 171. This passage communicates in turn, with a nipple 172 connected by the union 162 with the oil supply pipe 160.

A plug 174 is threaded in the end of the bore 169 and is provided outwardly of the body 164 with a knurled operating knob 175. As clearly shown in Figures 7 and 8, the plug 174 is provided with a plurality of longitudinal slots 176 com municating at their inner ends with the interior of the bore 169 and at their outer ends with the atmosphere through a passage 177 defined by the space between the knob and the adjacent end of the body 164.

A stem 178 is threaded in the plug 174 and extends entirely therethrough. The outer end of this stem is provided with a screw driver or similar slot 179, and a jam nut 180 is adapted to lock the stem 178 in properly adjusted position. The inner end of the stem 178 terminates in a metering pin 181 which is slidable in the passage 170. As shown in Figure 5, the metering pin partially covers the passage 171 to determine the rate of flow of oil therefrom. After the stem 178 has been set in proper position with respect to the plug 174, the latter may be rotated to increase or reduce the size of the air passage 177 and to simultaneously and proportionately increase or decrease the supply of air through the passage 171.

The operation of the apparatus is as follows:

Oil is fed by gravity from a suitable storage tank to the pipe 112, from whence it is delivered into the cooling jacket 111 of the compressor through the port 114. The oil circulates through the jacket 111 and is discharged through the outlet port 115 to the pipe 116. It will be apparent that the oil passing through the cooling jacket absorbs a considerable portion of the heat generated by the compressor during its operation. Thus the compressor is prevented from operating under excessive temperature conditions.

The movement of oil between the source and the operating parts of the compressor is determined by the action of the receptacle 146 and associated elements. When the level of the oil in the receptacle 146 is below that indicated by the line 164, the spring 148 overcomes the weight of the oil and the receptacle, thus moving the latter upwardly to the point where the valves 154 and 155 will be held in open position, and thus oil will flow from the pipe 116 into the chamber 136, and thence downwardly into the receptacle 146.

As the oil accumulates in the receptacle 146, the latter is gradually moved downwardly by overcoming the tension of the spring 148, and the tension of the spring is so adjusted that the valves 154 and 155 are adapted to close when the level of the oil in the receptacle reaches the point indicated by the line 164, this level being below the center of the air and oil proportioning device 163, for a purpose to be described.

As the receptacle 146 moves downwardly, it will be apparent that the valve stem 153 also will move downwardly, and when substantially the proper amount of oil is present in the receptacle 146, the valve 155 will engage its seat 151. If any foreign material should be present between the valve 155 and its seat so as to prevent proper engagement between these elements, oil will continue to flow into the receptacle, .thus increasing the weight of the latter to move it downwardly whereupon the valve 154 will engage its seat 150 to preill-.5

.removing the screw 157, whereupon the handle 145 may be moved to revolve the sleeve 143. This sleeve is threaded on the stem 141, and rotation of the sleeve obviously moves it upwardly or downwardly to vary the tension of the spring 148, and thus determine the weight of the oil in the receptacle 146 necessary to close the valves to prevent the further flow of oil.

As will become apparent, the operation of the compressor creates a partial vacuum in the passage 117 to draw oil into the interior of the compressor through the port 120. The pipe 160 has its lower end 161 projecting into the receptacle 146, and the other end of the pipe 160 supplies oil to the passages 171 and 170, and thus to the interior of the nipple 165. from which the oil is delivered to the passage 117.

It will be apparent that the rate of flow of oil into the compressor will be determined by the position of the metering pin 181 with respect to the passage 171, and this rate of fiow readily may be controlled by rotation of the knob 175 to move the metering pin inwardly or outwardly. This adjustment also varies the effective area of the air inlets 177, and accordingly the proper proportion of primary air will be supplied to the inlet passage 117. In this connection, attention is invited to the fact that the proper proportion of oil and air is determined by adjustment of the stem 178. To secure this adjustment, the lock nut 180 is loosened to permit adjustment of the stem 178 with respect to the plug 174, and when the proper adjustment is obtained,-the nut 180 is tightened to prevent further movement between the stem and the plug. This adjustment is permanent, and it will be apparent that adjustment of the knob 175 may be employed to vary the rate of flow of the oil and air, but the proportionate supply of the oil and air will not be disturbed upon adjustment of the knob 175.

The air supplied by the proportioning device flows into the inlet 1'77, through the passages 176 and thus into the chamber 169, and from this chamber the air flows through the passages 168 into the nipple 165. Oil flows in the manner previously described and mixes with the air as it flows into the nipple 165, and thus it will be apparent that the compressor pumps the mixture of oil and primary air through the outlet passage 118 to the pipe 13 leading to the burner.

The compressor is driven by the motor 102 and rotates in a clockwise direction as viewed in Figure 3. As the rotor operates, each vane 128 will alternately move inwardly and outwardly radially with respect to the shaft 126, and the spring 129 serves to retain the outer ends of the vanes in engagement with the wall of the compression chamber. This spring, as previously stated, remains substantially circular under all conditions, thus minimizing deformity of the spring and preventing crystallization and breakage thereof.

As each successive vane 128 passes beyond the intake port 120, an oil and air chamber will be defined between the vane, the rotor and the walls of the intake passage, and the volume of this chamber increases as the vane moves upwardly,

and thus oil and air will be drawn into the chamber referred to through the intake port. As soon as the vane has passed beyond the intake port 120, the next vane operates in the same manner. The oil and air thus will be carried around the compression chamber, and the space between each adjacent pair of vanes decreases in volume as it approaches the discharge port 119, thus creating a pressure in the body of the oil and air to discharge it through the port 119 to the passage 118, from which it flows to the pipe 13 in the manner previously stated.

One of the objects of the present invention is to provide a substantially standardized system which is adapted for use under different operating conditions. In this connection it will be apparent that some installations consume greater amounts of oil than others, in which case it is essential that means be provided for pumping the required amount of oil to the burner. As previously stated, the head 106 is secured to the base 95, while the body 105 of the compressor is secured to the head but not to the base 95. Accordingly it will be apparent that compressor bodies of the same diameter and of different lengths are adapted to be connected to the same head 106 whereby the desired pumping capacity may be obtained according to the particular installation of the apparatus.

With respect to the oil supply means, it will be apparent that oil is transferred from the receptacle 146 to the compressor by virtue of the suction created at the intake side of the latter. The motor 102 is preferably thermostatically controlled, and when desired temperatures are reached, the circuit to the motor 102 is broken by the thermostatic control means. Under such conditions it obviously is desirable that no oil shall be fed to the compressor, and for this reason, the level of the oil in the receptacle 146 is maintained below the level of the center of the oil and air proportioning device,' and accordingly no siphoning action can be set up when the compressor is not in operation, and thus the flow of oil into the proportioning device is prevented except when the compressor is in operation.

It will be apparent that the pipe 13 is connected to a liquid fuel consuming device which usually will be an oil burner to which oil and air under pressure are to be supplied. The apparatus of course, is efliciently operative in connection with any such type of oil burner.

The various elements of the system described cooperate with each other to provide a high degree of combustion efficiency. Overheating of the compressor is prevented by utilizing the oil as a cooling medium, while failure of the compressor due to the breakage of springs is prevented by utilizing the type of spring illustrated for moving the vanes of the compressor outwardly. The rate of flow of oil to the burner readily may be controlled together with the flow of primary air by adjustment of the proportioning device, without destroying the proportion of the air and oil. Proper combustion within the furnace is provided by the proper atomization of the fuel and the proper shape and angle of projection of the flame, while efiicient and dependable ignition is provided by the use of the electrodes in combination with the pilot burner. The efliciency of the burner operation is further increased by the means for supplying and controlling the secondary air for supporting combustion within the combustion chamber.

It is to be understood that the forms of the invention herewith shown and described are to be taken as preferred examples of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. Apparatus of the character described comprising a compressor having a pumping chamber and a cooling jacket each provided with inlet and outlet openings, means for supplying a liquid from a source to the inlet opening of said cooling jacket, a receptacle, means for delivering liquid from the outlet opening of said jacket to said receptacle, a conduit for supplying liquid from said receptacle to the inlet opening of said pumping chamber, and means for governing the supply of liquid to said receptacle in accordance with the rate of discharge of liquid from the outlet opening of said pumping chamber.

2. Apparatus of the character described comprising a compressor having a pumping chamber and a cooling jacket each provided with inlet and outlet openings, means for supplying oil from a source to the inlet opening of said cooling jacket, a receptacle, means for delivering oil from the outlet opening of said jacket to said receptacle, a conduit for supplying liquid from said receptacle to the inlet opening of said pumping chamber, means for introducing air into said pumping chamber through the inlet opening thereof in proportion to the amount of oil supplied to said chamber, and means for governing the supply of oil to said receptacle in accordance with the rate of discharge of liquid from the outlet opening of said pumping chamber.

3. In a system for supplying oil and primary air to a burner, a pump for transmitting oil and air to the burner under pressure, an inlet conduit for said pump, an oil and air mixing device connected to said inlet conduit, means including a receptacle for supplying oil to said device to be transferred .to said inlet conduit, said mixing device including means for supplying air to said conduit through said mixing device, independently operable adjusting means for controlling the flow of oil and air to said mixing device, and means for connecting said adjusting means to each other for simultaneous operation whereby the flow of oil and air to said mixing device may be varied without changing the proportions of oil and air, and means for maintaining the level of the oil in said receptacle below the level of the air supply means.

4-.. In a system for supplying oil and primar air to a burner, a body having an inlet end and an outlet end, a plug arranged in said body and provided with a passage therethrough, said plug being further provided with a longitudinal opening having a radial opening communicating therewith intermediate its ends, means for supplying oil to said radial opening, an adjustable plug mounted in the inlet end of said body and having an enlarged outer end arranged adjacent the end of said body and forming therewith an air inlet opening, said adjustable plug being provided with a longitudinal passage affording communication between said air inlet opening and said passage, a stem threaded through said adjustable plug and having its inner end slidable in said longitudinal opening to vary the amount of oil flowing thereinto from said radial opening, and means for securing said stem to said adjustable plug to move therewith longitudinally with respect to said body.

5. In a system for supplying oil and primary air to a burner, a pump for transmitting oil and air to the burner under pressure, an inlet conduit for said pump, an oil and air mixing device connected to said inlet conduit, means for supplying oil to said device to be transferred to said inlet conduit, said mixing device including means for supplying air to said conduit through said mixing device, independently operable adjusting means for controlling the flow of oil and air to said mixing device, and means for connecting said adjusting means to each other for simultaneous operation whereby the flow of oil and air to said mixing device may be varied without changing the proportions of oil and air.

6. In a system for supplying oil and primary air to a burner, a body having oil and air passages therethrough, an air adjusting member movable with respect to the body for varying the rate of air supply through said air passage, a metering member for controlling the rate of flow of oil through said oil passage and adjustable independently of said air adjusting member, and means for connecting said metering member and said air adjusting member together for simultaneous adjustment whereby the flow of oil and air through said passages may be varied without disturbing the proportions of the oil and air.

7. In a system for supplying oil and primary air to a burner, a body having oil and air passages therethrough, an air adjusting member carried by said body and movable with respect thereto to vary the flow of air through said air passage, a metering member carried by said air adjusting member and operable independently thereof for varying the flow of oil through said oil passage, and means for locking said metering member and said air adjusting member together for simultanenous adjustment whereby the flow of oil and air through said passages may be varied without disturbing the proportions of the oil and air.

8. In a system for supplying oil and primary air to a burner, a body having oil and air passages therethrough, an air adjusting member threaded in one end of said body and rotatable for varying the flow of air through said airpassage, a metering member having one end threaded through said air afiusting member and rotatable with respect thereto for varying the flow of oil through said oil passage, and a lock nut for connecting said air adjusting member and said metering member together to operate as a unit when said air adjusting member is rotated to vary the flow of oil and air through said passages without disturbing the proportions of the oil and air.

9. In a system for supplying oil and primary air to a burner, a body having oil and air passages therethrough, an air adjusting member axially adjustable with respect to said body for varying the flow of airthrough said air passage, a metering membercarried by said air adjusting member and axially adjustable for varying the flow of oil through said oil passage, and locking means for connecting said air adjusting member and said metering member together to operate as a unit when either member is adjusted to vary the flow of oil and air through said passages without disturbing the proportions of the oil and air.

JACOB L. MUELLER. 

